The present invention relates to an apparatus for the unwinding of flexible sheet-like structures, in particular printing products in imbricated formation, wound up together with a winding band onto a winding core to form a roll, according to the preamble of claim 1.
An unwinding apparatus of this type is known for example from EP-A1 0 292 891, which corresponds to U.S. Pat. No. 4,901,935. This apparatus has two mutually parallel and spaced apart, endless carrying bands, which are led around rollers mounted at the same height on a rack. For the unwinding of printing products wound-up in imbricated formation together with a winding band onto a winding core to form a roll from said roll, the winding unit formed by the winding core and the roll is set down onto the effective carrying sides of the carrying bands. The roll thereby rests with its circumference on the carrying bands and is wrapped partly around by the latter for driving the winding unit. The rollers around which the two carrying bands are led, at the end of the effective conveying sides seen in the unwinding sense of the printing products, are seated in a rotationally fixed manner on a common shaft, which is coupled to a drive motor. A band reel, which is likewise connected to the drive motor, via a friction clutch, is seated freely rotatably on the shaft between these two rollers. Once the winding unit has been set down onto the carrying bands, the initial region of the winding band, which is lashed to the roll, is manually released, brought to the band reel and connected to it. Since the band reel is driven faster, via the friction clutch, than the carrying bands during the unwinding operation, the winding band is constantly kept under tension. As soon as all the printing products have been unwound from the roll, the end of the winding band on the winding core side is released from the winding core and the latter is lifted off the carrying bands. The full band reel must then be exchanged for an empty one in order to be able to take up the winding band of the next roll to be unwound. Consequently, a considerable amount of manual work is necessary, to release the lashed winding band and to fasten the winding band end onto the band reel.
In addition, an apparatus for the winding-up and unwinding of printing products together with a winding band to form a roll or from a roll is known from EP-A1 0 281 790, which corresponds to U.S. Pat. No. 4,898,336. This apparatus has a carriage which is displaceable in the vertical direction on a rack and on which a bearing arrangement is provided for the winding core carrying the roll. The bearing arrangement has a drive motor, in order to drive on the winding core side the winding unit set down onto the bearing arrangement. Underneath the bearing arrangement there is provided a belt conveyor which has two loose conveyor belts spaced laterally apart, and which is mounted in the manner of a rocker and is prestressed against the roll. The winding bands are driven solely by the roll, due to wrapping partly around it. Mounted freely rotatably on the rocker of the belt conveyor is a deflection roller, around which the winding band coming from the roll is led and from which the winding band runs to a band reel mounted fixedly on the rack and driven via a drive motor. For unwinding, the winding unit with the winding core is set down onto the bearing arrangement, the carriage being located in its uppermost end position. Thereafter, the carriage is lowered to the extent that the roll comes into contact with the conveyor belts of the belt conveyor and the belt conveyor is thereby pivoted into a lower end position. Then the winding band end lashed to the roll is released and brought around the deflection roller to the band reel and fastened there. During the unwinding operation, the winding unit is driven via the drive of the bearing arrangement in the unwinding sense and the belt conveyor, due to its bearing against the circumference of the roll, for conveying away the unwound printing products also runs at the circumferential speed of the winding unit. The winding band is kept under tension by the drive of the band reel. As soon as the rocker of the band conveyor has pivoted upward by a certain amount during unwinding, due to the reduction in diameter of the roll, the carriage is lowered further, until the belt conveyor is again located in its lower end position. In the case of this known apparatus as well, the work in detaching the winding band from the roll and fastening the winding band end to the band reel involves considerable effort. Furthermore, the known apparatus is complicated in construction and complex in terms of its drive.
In addition, a touch-and-close fastener for a winding band is described in EP-A1 0 310 784, which corresponds to U.S. patent application Ser. No. 07/585,033, now U.S. Pat. No. 5,081,748. The winding band is wound-up together with printing products on a roll and has at its outer end region, on the side facing the roll, a hook pile, which interacts with a loop pile, which is provided on the outside of the winding band. The loop pile extends over a certain length of the winding band, so that the hook pile always bears against a region of the loop pile, irrespective of the diameter of the roll. The hook pile and loop pile flank a spacer, the thickness of which at most corresponds to the height of the assigned pile. To open the touch-and-close fastener, a trowel-like tool is inserted from the end of the winding band between the spacer assigned to the hook pile and the spacer assigned to the loop pile.
Swiss Patent Specification 652,379 and the corresponding U.S. Pat. No. 4,532,750 disclose an apparatus for the winding up of printing products in imbricated formation onto a winding core, in which, before winding-up, the winding band is drawn off a supply reel provided inside the winding core and is wound onto a band reel. To detach the winding band from the supply reel, there is provided inside the winding core a pin which is prestressed against the supply reel and, when the supply reel rotates, by means of a separate drive, pierces between the winding band end and the supply reel. The detached winding band end is led out from the winding core through an opening, seized by a pair of advancing rollers and led by a guide running along a rocker, for feeding the printing products to the roll, and by means of a further rocker to the circumference of the band reel. When a number of windings of the winding band have been wound onto the band reel, the separate drive is pivoted together with the driven roller of the pair of advancing rollers out of the area of the winding core. If the winding band has a touch-and-close fastener in order to keep the winding band on the supply reel, it is provided away from the winding band end, in order that the pin can detach the winding band end and the pair of advancing rollers can seize the winding band before the touch-and-close fastener is to be opened. Furthermore, a similarly designed detaching device, arranged on the rocker for feeding the printing products to the winding core, for detaching the winding band end from a winding band supply arranged in a covered circumferential groove of the winding core is known from EP-A1 0 280 949 and the corresponding U.S. Pat. No. 4,795,105. The band end detached from the next winding layer of the winding band supply is deflected and fed to a band reel remote from the rocker.
It is an object of the present invention to provide an apparatus of the generic type described above which is extremely easy to operate and simple in construction.